Early Detection of Avian Oncogenic Viruses from Blood of Apparently Healthy Chickens

Viral neoplasms in commercial poultry are mainly caused by members of two families with Marek’s disease virus (MDV) belonging to Herpesviridae and reticuloendotheliosis virus (REV), avian leukosis virus subgroups A to E and avian leukosis virus subgroup J (ALV-J) belonging to Retroviridae. This study was conducted to know the status of neoplasms caused by avian oncogenic viruses in commercial chickens. 25 blood samples were collected from a broiler breeder flock that appeared healthy but chickens from the flock on necropsy showed visceral tumours. PCR was employed on blood DNAs of these chickens for detection of avian oncogenic viruses which eventually detected the presence of multiple oncogenic virus infection in most birds. MDV specific primers that could differentiate between pathogenic and non-pathogenic serotype-1 virus detected MDV in four blood DNAs. REV could be detected from all the 25 blood DNAs and endogenous ALV was detected in 21 blood DNAs signifying the slow transforming nature of the retroviruses that may take months to perpetuate visible tumours. It was concluded that concurrent presence of multiple oncogenic viruses in the same bird is more common than the presence of single virus. Thus, for early disease control programs, this moderately simple PCR diagnostic technique can be utilized to identify the birds undergoing latent infection with avian oncogenic viruses.     

Hyperglycemia exaggerates ischemia-reperfusion-induced cardiomyocyte injury: reversal with endothelin antagonism

OBJECTIVES: We have previously demonstrated an importance of endothelin-1 in diabetic patients undergoing bypass surgery. Recent evidence suggests that cardiomyocytes might also produce endothelin-1, which might directly impair myocyte contractility by increasing intracellular calcium levels. Because hyperglycemia is a potent stimulus of endothelin-1 production, we hypothesized that increased production, action, or both of endothelin-1 might be a mediator of direct cardiomyocyte injury in diabetes. Therefore we studied the effects of endothelin receptor blockers (BQ-123 and bosentan) on hyperglycemia-induced endothelin-1 production and cellular injury after ischemia-reperfusion. METHODS: Using a human ventricular heart cell model of simulated ischemia-reperfusion, we studied the effects of normoglycemia (5 mmol/L, 48 hours) and hyperglycemia (25 mmol/L, 48 hours) on cellular injury and endothelin-1 production. Furthermore, the effects of selective endothelin-A and mixed endothelin-A/B receptor antagonism (with BQ-123 and bosentan, respectively) were evaluated. RESULTS: Cellular injury, as assessed by means of trypan blue uptake, was higher in human ventricular heart cells subjected to hyperglycemia and simulated ischemia-reperfusion injury (P =.01); this effect was prevented with both BQ-123 and bosentan (P =.01). In addition, heart cells from the hyperglycemic group elaborated more endothelin-1 after ischemia-reperfusion (P =.02). CONCLUSIONS: Endothelin-1 production and cellular injury were greater in human ventricular heart cells subjected to hyperglycemic conditions and simulated ischemia-reperfusion. These effects are mediated by endothelin-A receptors because both BQ-123 and bosentan exerted similar degrees of protection. Endothelin receptor blockade is a novel strategy to improve the resistance of the diabetic heart to cardioplegic arrest and reperfusion.     

Ursodeoxycholic Acid Enhances Fractional Calcium Absorption in Primary Biliary Cirrhosis

Bone disease is a frequently reported complication in primary biliary cirrhosis (PBC), but its pathogenesis is poorly understood. Calcium malabsorption has been considered as an important contributing factor. Ursodeoxycholic acid (UDCA) is the treatment of choice in PBC, improving survival, but its effect on calcium absorption is unknown. In this study, we have measured fractional calcium absorption, using a single isotope method, in a group of female PBC patients (median age: 60 years, range: 46–78 years) and age-matched female controls (median age: 58 years, range: 36–74). Bone mineral density (BMD) in PBC patients was significantly lower than age-matched controls (g/cm²± SEM; lumbar spine: controls 1.139 ± 0.028, PBC patients 1.004 ± 0.026, p= 0.0028; femoral neck: controls 0.944 ± 0.034, PBC patients 0.819 ± 0.023, p = 0.0032). Twenty two PBC patients, who were not vitamin D-deficient, were off and on UDCA for ~1 month and ~8 weeks, respectively. Fractional calcium absorption in PBC patients prior to UDCA treatment (mean ± SEM, 33.8 ± 2.6%) was significantly lower than controls (52.0 ± 2.4%, p<0.001). Following UDCA therapy, fractional calcium absorption increased significantly (Off UDCA: 33.1 ± 2.6%, On UDCA: 36.6 ± 2.5%, p<0.0058). Osteocalcin levels were significantly raised in the PBC group (mean ± SEM, ng/ml, 41.4 ± 2.02) compared to controls (31.1 ± 2.64, p= 0.002). There were no differences in parathyroid hormone (PTH) or 25-hydroxyvitamin D levels between these two groups or following UDCA therapy. In conclusion, we found that PBC patients display low spinal and femoral neck BMD, reduced fractional calcium absorption, and elevated plasma osteocalcin. The calcium malabsorption is corrected partially by UDCA therapy. Long-term studies are required to determine whether this effect can be sustained, and whether a sustained increase in fractional calcium absorption can translate into a favorable change in bone strength in patients with PBC. Received: 27 November 2001 / Accepted: 11 April 2002     

Correlation between change in graft height and change in segmental angle following central corpectomy for cervical spondylotic myelopathy

OBJECT: This study was undertaken to examine the correlation between change in graft height and change in angulation across grafted segments (segmental angle) in patients undergoing central corpectomy (CC) with autologous bone reconstruction for cervical spondylotic myelopathy (CSM). METHODS: The authors performed a retrospective analysis of 70 cases in which patients with CSM underwent uninstrumented single- or multilevel CC and had evidence of osseous fusion of their grafts at follow-up. The segmental angles and heights of the grafted segments on preoperative, postoperative, and follow-up radiographs were compared. RESULTS: The mean change in graft height (+/- standard deviation) was -7.3 +/- 3.8 mm (mean duration of follow-up 19.7 +/- 5.4 months, range 13-53 months). There was a mean kyphotic change in segmental angle of -7.3 +/- 3.8 degrees (p < 0.001). In patients who had a straight or kyphotic cervical spine (28 patients) or a straight or kyphotic segment (32 patients) preoperatively, there was a significant linear correlation between changes in graft height and changes in segmental angle (Pearson correlation, r = 0.40, p = 0.03; r = 0.40, p = 0.02, respectively). Such a correlation was not seen in the patients who had a lordotic cervical spine (42 patients) or a lordotic segment (38 patients) preoperatively (Pearson correlation, r = -0.04, p = 0.81; r = 0.08, p = 0.62, respectively). The change in segmental angle did not influence improvement in Nurick grade (p = 0.8). The degree of agreement between the 2 observers was almost perfect for measurement of graft height (postoperative intraclass correlation coefficient [ICC] = 0.94, follow-up ICC = 0.90) but was significantly lower for measurement of segmental angles (postoperative ICC = 0.71, follow-up ICC = 0.67). CONCLUSIONS: Among patients undergoing uninstrumented CC for CSM, there is a significant correlation between postoperative settling and kyphotic change across fused segments in those who had straight or kyphotic cervical spines or segments preoperatively but not in those who had lordotic cervical spines or segments preoperatively. A more vigorous surgical correction of the segmental kyphosis than achieved in this study might have caused the kyphotic segments to behave like the lordotic segments. Paraspinal muscles and ligaments may play a role in determining the segmental angle as graft settling in patients with lordotic spines or segments is not linearly correlated with angular change.     

Efficient insertion of genes into the mouse germ line via retroviral vectors.

We present a general strategy for the efficient insertion of recombinant retroviral vector DNA into the mouse germ line via infection of preimplantation mouse embryos. Transgenic mice were generated that harbor a replication-competent recombinant retrovirus (delta Mo + Py M-MuLV) that lacks the Moloney murine leukemia virus (M-MuLV)-type enhancer sequence in the long terminal repeat (LTR). Instead, the LTR contains an enhancer element that permits polyoma virus F101 to grow in undifferentiated F9 embryonal carcinoma cells. Expression studies in different tissues of animals transgenic for delta Mo + Py M-MuLV indicate possibilities to target and modulate expression of retroviral recombinants in mice via their LTR enhancer sequences. In addition, 16 transgenic mice were generated that harbor proviral DNA of a defective recombinant retrovirus carrying a mutant dihydrofolate reductase gene.     

Proximal femoral fractures: Principles of management and review of literature

PurposeThe purpose of this study was to review the principles involved in the management of proximal femoral fractures as reported in the literature. Methods: A medical literature search in the MEDLINE (PubMed) and Cochrane database was undertaken to review strategies and principles in proximal femoral fracture treatment. Randomized control trials and meta analysis were given preference while case reports/small series were rejected. Results and conclusions: Early anatomical reduction and surgical fixation remains the best option to reduce the risk of complications like non-union and avascular necrosis in treating fracture neck femurs. Cancellous screws continue to be the preferred treatment for fixation of neck femur fractures in younger population until the benefit of using sliding hip screws is validated by large multicentric studies. In the geriatric age group, early prosthetic replacement brings down the mortality and morbidity associated with neck femur fractures. Sliding hip screw (DHS) is the best available option for stable inter trochanteric fractures. The use of intramedullary nails e.g. PFN is beneficial in treating inter trochanteric fractures with comminution and loss of lateral buttress. Intramedullary implants have been proven to have increased success rates in subtrochanteric fractures and should be preferred over extramedullary plate fixation systems.     

Chronic endothelin antagonism restores cerebrovascular function in diabetes

OBJECTIVE: Diabetes profoundly alters vascular function and is a risk factor for cerebrovascular disease. Diabetes increases myogenic tone and decreases responsiveness to adenosine triphosphatase (ATP)-sensitive K(+) (K(ATP)) channel openers and endothelium-dependent vasodilators. The mechanism(s) by which diabetes impairs cerebrovascular function remain obscure. In the present study, the effects of the potent vasoactive peptide endothelin-1 on myogenic tone and endothelium-dependent and potassium channel-mediated vasodilation in middle cerebral arteries from diabetic and nondiabetic rats were investigated. METHODS: Twenty-eight Wistar rats were divided into four experimental groups (n = 7 per group): control (C), control treated with bosentan (an endothelin A/B receptor antagonist) (CB), diabetic (D), and diabetic bosentan-treated (DB). Diabetes was induced with streptozotocin (D and DB groups), after which chronic bosentan treatment was initiated (CB and DB groups). Middle cerebral arteries were mounted in a pressure myograph, and myogenic responses were recorded. In addition, endothelium-dependent and -independent responses and the effects of the K(ATP) channel opener pinacidil were examined. RESULTS: Cerebral arteries from the diabetic and nondiabetic rats constricted in response to graded pressure increases. Maximum myogenic responses (percent constriction at 60 mm Hg) were significantly greater in the D group (38 +/- 3% versus 25 +/- 3% in C; P < 0.02). The enhanced myogenic tone in the D group was completely prevented by bosentan treatment (DB, 23 +/- 5% versus D; P < 0.003) without an effect on the CB group. In addition, bosentan treatment improved endothelium-dependent vasomotion and improved K(ATP)-mediated vasodilation in the DB group (P < 0.001). CONCLUSION: These data describe, for the first time, the interaction between endothelin-1, myogenic tone, and endothelial function in diabetes. Chronic endothelin antagonism restores cerebrovascular function in this model of diabetes and has global implications for the management of cerebrovascular disease in diabetes.